When temperatures get too high and stay high year after year,
whole forests in North America could be devastated, the
researchers said. Heat or drought weakens trees, making them more
susceptible to fire, disease, and insects, thereby preventing
healthy growth, and diminishing their absorption rate of carbon
dioxide.

“There is a critical and potentially detrimental feedback loop
going on here,” Noah Charney, study author and researcher at the
University of Arizona,
said in a press release.

In fact, forests could actually turn into a source of CO2 in the
atmosphere — maybe as soon as 2050 — because the trees could die
faster than they could absorb carbon dioxide. If they die, they
would release trapped carbon, adding to the vicious cycle and
helping accelerating climate change.

The newly published study combined widely-used climate projection
models, tapped 1,457 sample sites across the continent, and
utilized the North American historic tree-ring records from 1900
to 1950 to arrive at their results.

Projected
change in forest growth rates for the second half of this
century. With the exception of coastal areas, growth rates are
projected to go down throughout the North American
continent.Noah
Charney

Under a worst case scenario, the study researchers said that by
2075, the average temperature in North America could be about
43 degrees Fahrenheit higher than it was in 1925. Trees in
the north and southwest (including the Rocky Mountains, Canada,
and Alaska) could grow as much as 75% slower than normal as a
result.

The study challenged previous research, which had suggested that
trees in colder areas could grow larger with warming temperatures
and absorb more CO2.

The researchers say their work adds to the evidence that carbon
emissions need to be monitored in order to have any impact on
limiting the effects of a continually warming world.